Press



Feb. 3, 1942. l s. E. McLAuGHLlN 2,271,656

PRESS Filed May ,27, 1940 3 sheets-sheet 2 Feb. A3, 1942. G. E.MCLAUGHLIN l PRE'vss Filed May 27, 1940 3 Sheets-Sheet 3 Patented Feb.3, 1942 PRESS George E. McLaughlin, Brookline, Mass., assignor to TheTurner Tanning Machinery Company, Portland; Maine, a corporation ofMaine Application May 27, 1940,`Serial No. 337,501 l 54 Claims.

This inventoin is embodiedvin a press wherein mechanical means isemployed to move one of the platens into co-operative relation toanother platen,`the latter being hydraulically operated during pressureapplying operations upon given pieces of work, and in which electricalcontrolling means is provided to secure operation of the mechanicalmeans and of the hydraulic means in properly timed relation each other.In certain kinds of work, for example, where the work pieces are tannedhides or skins, one of the platens will be heated, preferably the upperplaten, since application of heat to the surface of theleather iscommonly advantageous both in plating and embossing operations uponleather.

It is an important feature ofthe invention that electrical controllingmeans is provided to operate the mechanical operating means for one ofthe platens and also the hydraulic means for the other platen in suchmanner that initiation of a pressure applying operation is followed byoperations of the press in the full automatic cycle during .which thepress operates repeatedly at regular short intervals to apply lightpressure to the hide or skin, the latter being shifted betweensuccessive pressure applying operations tov This treatment of a When itis desired to employ a more substlantial pressure iny kiss-platingoperations upon light leathers, provision is made for introducing a lowrange pressure governor. in both the hydraulic and electrical circuitsof the press so'that pressure may be 'built u p to a point regulatableby adjustment of the pressuregovernor.' The electrical circuit alsoincludes a repeating relay for control of the mechanical means operatingone a manual control member may be so manipulated as to initiaterepeated operations of the press in the full ,automatic cycle, therebyexpeditlng treatment of the skins since the operator readilyaccommodates himself to the periodic opening and closing ofthe press toshift the lwork piece, thereby to secure treatment of all parts thereofand to remove and introduce successive pieces of work.

Preferably, and as shown, the press embodies a high range pressuregovernor as well as a low range pressure governor with means to selectone or the other according to the type of work to be done. Thearrangement of the electrical means, however, is such that cutting-in ofthe high range pressure governor results in making the repeating vrelayineffective so that the press operates semi-automatically, that is, itopens automatically at the end of the cycle under control of thepressure governor but each cycle must be initiated by propermanipulation of the manual control member in the electrical circuit. 'Itis to be understood, however, that by proper manipulation of a manualcontrol member a pressing operation may be terminated at any time in thejudgment of the operator without waiting for the termination of theoperation under control of the pressure governor.

Conveniently, the electrical circuit may be made to include two timerelays which may be cut in or out of the circuit by the use of selectorswitches. By the use of one of the time relays it is possible to securea dwell for a predetermined period while the work piece is subjected toa heated platen at low pressure, the purpose being to heat the surfaceof the leather as a preliminary to either a plating or an embossingoperation at higher pressures. The arrangement of the electrical meansis such that cutting-in of the time delay rela-y for a dwell at lowpressure automatically eliminatesthe repeating relay, with the resultthat the press can no longer operate in the full automatic cycle.Through the use of the proper selector switch, a time relay may be cutinto the electrical circuit to secure the application of maximumpressure, as determined by a high range pressure'.

governor, for a dwell of regulatable lengthl suitable to secure the bestresults in embossing operations upon light or heavy leathers.

It is also an important feature of this press,

vfrom the standpoint of safety, vthat it may be y caused to open at anytime through the operation kof the regular manual control or by theoperaof the p latens, the arrangement being such that "tion of enemergency button. The arrangement is such that the press may be causednot only to reverse the movement of the platens at any time during theclosing operation but also to open again instantly at any time after ithas closed. In order that an operator working under piece work rates maynot misuse his power to open the press, for example, by interrupting thebuilding up of rpressure to the desired maximum, thereby to speed up theoperations of the press, there is provided a gong which will sound ifthe press be opened .while it is still under control of the pressuregovernor. Where it is de,- sired, however, to leave to the judgment ofthe operator the amount of pressure and the length of time during whichit is applied to the pieces of a given batch of work, the gong may bedisconnected by a switch which is normally under lock and key. The pressmay then be operated by the usual manual control memberisuch as a foottreadle) to initiate and also to terminate each pressure applyingoperation.

It is to be understood that various important features of the inventionare applicable to a pressv of the type wherein mechanical means'operates one of the platens to close the gap. between it and astationary platen, hydraulic means being also provided in connectionwith the same movable platen to effect a pressure applying operation.Other features of the invention are also applicable to a press whereinhydraulic means associated with one of the platens operates the latterboth to closethe gap between the platens and to effect a pressuretreatment of a work piece placed between the platens.

In the light of the foregoing brief description of the invention, itwill be evident that this press is characterized by marked flexibilitysince it may be readily adjusted to operate in any one ofl a number ofways to secure various results on different classesvof work. In the fullautomatic cycle, wherein the press operates repeatedly following asingle depression of a treadle or other controlling member, the operatoris freed from constant foot operation of the controlling treadle and maygive his attention to proper manipulation of' work pieces suitable fortreatment by regularly recurring pressing operations of short duration,this arrangement being especially advantageous in that the capacity ofthe press 'and of the operator are greatly increased. Through control ofa switch or of a valve in the hydraulic means, the operator mayinstantly change the press to one which operates semi-automatically,wherein a manual control member initiates each operation of the presswhich perform in a predetermined manner and comes to rest automatically.This manner of operating the press assures thev operator of greatersafety and permits him to take whatever time is required to present thework pieces for each pressure operation. By-the operation of a switch,thepress may be made to dwell while the work piece is undergoingtreatment by a heated platen at low pressure, while another switch maybe used to insure a dwell while the work piece is undergoing treatmentat maximum pressure. Furthermore, the time that it takes to build uppressure under control of either a low range pressure governor or ahigh' range pressure governor may be readily adjusted through propermanipulation of a control memlarly for .embossing and for the generalrun of smooth plating, while the full automatic cycleis especiallysuitable for kiss-plating of light skins after boarding.

These and other important features of the invention-and novelcombinations of parte will now b e described in detail in thespecification and then pointed out more particularly in theappended^claims.

In the drawings:A l

Fig. 1 is a view in side elevation ofa press showing one embodiment ofthe invention;

Fig. 2 is a front view, partly in section, of the press shown in Fig. 1;i A j Y Fig. 3 is a detail of a check valve:

Fig. 4 is a detail of a valve arrangement;

Fig. 5 is a detail of the pump;

Fig. 6 is a diagram showing `relative time operation of three limitswitches;

Figs. 7 and 8 are sectional views of a three-way valve showing a movablevalve member in two valve showing a movable valve member in differentpositions;

Fig. 11 shows in side elevation a rotary radial piston-pump provided tofurnish a pressure medium for the pres's operations;

Fig. 12 is a more or less diagrammatic view of the pump, the presscylinders, and the hydraulic circuit;

Fig. 13 is a sectional view of a regulating valve shown in the line inFig. l2;

' Fig. 14 is a sectionalview of a and clutch;

Fig. 15 is a sectional view of a valve for cutting a low range pressuregovernor into or out of the hydraulic circuit; and

Fig. 16 is a diagrammatic representation of electrical circuits foroperating the press.

In th illustrated embodiment of the invention, which s designedparticularly for smooth plating magnetic 'brake and embossing operationsupon hidesv and skins,

there is provided an'upper platen 10 carried at the forward end of aheavy lever member 1| movable about a pivot at 12 to carry the platen 10into and out of co-operative relation with respect to a lower platen 13.Preferably and as power, a clutch 'I6 and a brake 11 (Fig. 14) beingprovided under electrical control respectively to connect and disconnectthe pulley with respect to a shaft 18. l

As shown, a pinion 18 fast von the shaft 18 is in mesh with a large gearsecured to a shaft 82 which includes a crank to operate a link83-'pivotally connectedto a toggle 84, 84a to operate the lever member1i, it being understood that straightening of the toggle 84, 84a movesthe upper platen 10 into co-operative relation with the lower platen 13,while breaking of the toggle 84, 84a effects separating movement of thetwo platens. Movement of the platen 10 by the described mechanical meanshas the effect ofopening and closing a gap between the platens, suitablefor the introduction and removal of work pieces between pressureapplying operations.

As shown, the lower platen 13 'is carried by two rams or pistons 85(Figs. 1 and 2). It will be readily understood, however, that either alarge or a small hydraulic -press may make use of only one hydraulic ramor piston for operating the lower platen'. Each piston is movable in awell fitting cylinder 86, the usual U-packing'such as that shown at 81being provided to minimize the escape of the pressure medium under thethis press. Preferably each piston 85 is supported yieldingly by aspring 88 (Fig. 2), it being one of the purposes of the spring to insuregood coni-V tact of both upper and lower platens with a work pieceplaced on the lower platen, the arrangement being such as to accommodatethe press to work pieces within a relatively wide range of thicknesses,sumcient, for instance, for all thicknesses of leather. Preferably, andas shown, the

lower platen yields downwardly to a slight extent, when the upper platenengages the work piece on the lower platen. When the press is open, the

served that, when the movable valve piston |30 hydraulic circuit `may beso adjusted -that the' I pressure medium may be under pressure justsufiicient to "oat the pistons or rams 8 5, one purpose being to speedup the pressure applying operation.

. The pressure medium (preferably a suitable oil) is supplied to thecylinders 88 by a constantly running pump shown in side elevation at .90in Fig. 11. This pump is of the type known-Las a rotary radial pistonpump and capable of iurnishing about four gallons per minute. Since thepump is commercially well known, full tietails thereof are not shown inthe drawings. For

carrying a tight and a loose pulley 94, 88, respectively, adapted to bedriven from any suitable source of power, a vcoupling being provided at98 whereby the pump shaft |00 may-be driven from the shaft 92, the speedof the shaft being tion of these valves being shown in detail in Figs. 7to 10, inclusive. Conveniently, the valve pistons of the valves and |28are solenoid-operated,V as indicated at |21, |28, respectively, in Figs.12

anu 16.

Upon reference to Figs. 'land 8. it will .be obin the valve |25 is inits lowered position (Fig. '1), the ilow of oil is from the pumpdischarge pipe |20 to the pipe |2| and thence to the cylinders 88,whereas when the valve piston' |30 is in its raised position (Fig. 8),the ow of the oil is from the pump discharge |20 intoa pipe |3| whichopens into a return pipe |32 leading'back to the tank 80.'

Upon inspectionof Figs. 9 and 10, it will be observed thattheconstruction of the valve 28 is substantially the same as that ofthethreeway valve |25, the three-way valve shown in Figs. 7 and 8 havingbeen conveniently converted into a two-way valve. |28 simply by pluggingone of the outlets by a screw plug |33. When the valve -driving the pumpthere is provided a shaft 82 of the type shown in United States LettersPatent No. 1,250,170 granted December 18, 1917, upon application ofHele-Shaw and Martineaux. After adjustment of the wheel |02 the lattermay be locked in place by a lock member |04 (Fig. 5).

Located below the pump 00 there is shown a fifteen gallon tank |08 (Fig.11) for the lubricating oil which conveniently serves as the pressuremedium in this case, the quantity being large enough to insure thatthere is no overheating of the oil. At one end of the tank |08 there isa suction screen |08 covering the inner end of a pipe |50 (Figs. 11 and12) which conducts the oil to the pump 90, a return discharge pipe beingin dicated at ||2 (Fig. 12). Conveniently the tank E08 is provided withtwo baille plates |4 and with anoil level gage ||5. that the pump 90 isa constantly running pump with one direction of discharge. Furthermore,control through the wheel member |02 provides for adjustment of thestroke of the pump piston and hence determines the oil capacity of -thepump and therefore the time it willtake to build up pressure in thepiston cylinders 88, there being also an indicator (not shown) whichaffords anindication to the operator of the stroke setting of thepistons. With this pump, the pressure in the medium under the presspistons 85 may be as high as 3000 pounds per square inch.

Upon reference to Fig. 12 of the drawings, it will be observed that oilfrom the pump 90 passes throughthe discharge pipe |20, |2| to both .ofv

It is to be understood piston |34 in valve |28 is ln'its lower position(Fig. 9), oil entering from the pipe |2| passes through the valve |28and out through a pipe |35 to the pipe |32 which returns the oilto, thetank |08, in which case there is little or no pressure in the cylinders88. On the contrary, when the valve piston |34 is in its raised positionin the valve |28 (Fig. 10) oil entering the valve |26 from the pipe |2|is checked or blocked, with the result that pressure within the pipe |2|and hence in the cylinders 88 may be built upto the maximum pressure forwhich the press vis set.

1n order that oil may occupy the space below the piston 85 in eachcylinder 88, when the press is open, there is provided a regulatingvalve |31 (Figs. 2, 4, 12 and 13) operative to oier resistance to the owof oil from pipe |35 to pipe |32 sufficient to cause and maintainpressure in pipe |2| and pipes |23, during the continued operation o'fthe pump 80, so that not only are vthe said spaces below the pistons 85occupied by oil but the pressure may be so adjusted as just to iloat thepistons 85 in the cylinders 88.

When putting the press in commission, or 'when reiilling after havingdrained the oil from the press to make repairs, it is necessary toprovide for escape of air from the hydraulic circuit, For this purposean air relief cock |38 is conveniently provided on one of the cylinders62 asindicated in Figs. 2 and l2.

A check valve |39 is provided between the three-way valve |25 and vthepipe |23 leading to the first press cylinder 88, the check valve bethecylinders 88 through branch pipes |23, a pres- I ing so constructed thatoil may readily pass toward the cylinders but not in the reversedirection, thus insuring, as far as possible, maintenance of thepressure being built up within the pipe |2|. While very high pressure isbeing maintained in the pipe |2| and in the valves |25 and |25, there isbound to be some leakage with a corresponding drop in the pressure.`Such drop in pressure is overcome by pump action operating through thevalve |25, the check valve |39 having served toA maintain the pressurein the f pipe |2| even though oil was being by-passed through the pipes|3| and |32 back to. the tank |08. Hence when the dropped pressure is tobe restored, the pump has only to bring the pressure up the requiredlamount in the short portion of the pipe |20 between the pump and thecheck valve |39 in order to build it up to (and beyond) the pressuremaintained in the pipe |2| by said |25 and also a two-way valve |28, theconstruccheck valve |39. By vthis arrangement, there is no drop in thepressure in the pipe I2 I. and press cylinders 86 except that' caused bysome slight leakage, whereas if there were no check valve |39, theremight be quite a drop in pressurein the cylinders 86 at the time ofthestarting of the pressure buildup to replace leakage'loss.

There is shown at |40 (Figs. 2 and 12) a relief valve having a chainconnection (Fig. 2) to the lower platen 13. When the press is open, `thechain1is. slack, so that the lower platen would have to 'rise apredetermined distance beyond the normal before the relief valve wouldbecome operative. This prevents lifting of the lower platen to an extentsuch that damage might result to the press through premature contact ofthe lower platen with the descending -upper platen, which ismechanically operated .to a pree determined low position. In case therelief valve |40 is operated, liquid is discharged through pipe |4| toan outside container (not shown). For further details of this valvemechanism reference should be had to Patent No. 1,115,013., granted uponapplication of F. Perkins.

In the operation of the press in embossing hides or skins, there is,during the rst stage, a relatively small pressure on the piece ofleather being treated, this being due to the fact that, at the time theupper platen descends into contact with the workpiece, there is acertain denite pressure in the pressure medium to float the pistons intheir cylinders. At this'stage, the piston valve |30 of valve |25 is inlower position (Fig. '7), whereby the pressure medium' is passingthrough valve 25 by way of pipes |20, |2|, and through valve |26 and byway of pipe |35 to the pipe |32 to return to tank |06. As stated above,pressure in the hydraulic circuit at this stage is due to the regulatingvalve |31, which is a well-known commercial unit commonlydesignated aback-pressure valve. This will be clear upon inspection of Fig. 13,wherein the valve |31 is shown to comprise a valve piston |31 having ahead |31b which may be seated in a countersunk opening at |4| to closethe valve against movement of oil from pipe |35 to pipe |32. However, bymeans of a small pipe |43, the pressure medium enters the bottom of theregulating valve |31 and, because of the large area of a flexible wallor diaphragm |45, thepressure (which is the same as in the pipe |35)lifts the valvehead I31b, against the pressure of a regulatable'spring|41, from the seat |4| and thus permits restricted flow of the pressuremedium from pipe |35 to pipe |32', whereby a back pressure is producedin the cylinders 86, just suiiicient to lift the pistons 85 with the aidof the springs 88 and to maintain the latter in floating condition. Theweight of the lower platen and pistons is suiiicient to compress thesprings 88 (1i'ig.`2).l On the other hand, the back pressure in thehydraulic medium, due to the valve I 31, counterbalances a definite (butregulatable) part of such weight so thatthe springs 88 are enabled tolift these parts to a deflnite position, for instance, to a positionsuch that the lower platen is contacted and forced downwardly by theupper platen as the latter reaches its lowest position. This resuits injumping the pressure on the work piece at the very beginning of apressure applysubstituted therefor;

lowering of the upper platen 10 into contact with the leather on thelower platen 13, fthe upper platen moving to a predetermined positionand thus forcing downwardly the lower platen against oil in thecylinders86. It is to -be understood, however, that back pressure in'thepipe |35 (and hence in the piston cylinders 86) may be eliminated byadjusting a manually operable stop |49 upwardly to a. position Where itlifts the diaphragm |45 and the piston |31 upwardly to a position'wherethe head |31b is lifted to oer-no obstruction to the flow of oil frompipe |35 to pipe |32. In that case, there will be no back pressure inthe pipe |35 and in the cylinders 86.

In the second stage, pressure is being built up in the hydrauliccircuit, including the piston cylinders 86. During this stage the piston|30 in valve |25 is in lowered position (Fig, '1) so that oil passesfrom the pipe |20 through the check valve |39 (Figs. 3 and 12) to thepipe |2|, while at the same time the valve piston |34 in the valve |26is in raised position (Fig. 10) thereby blocking the flow of oil to pine|35. Hence, pressure is built up in the pipes |2| and |23 and thecylinders 86 to a point predetermined beforehand (for example, by theuse of a pressure governor), although it is also under the control ofthe operator, as will hereinafter be pointed out. In this stage, duringwhich pressure is built up, the length of time involved in arriving atmaximum pressure maybe predetermined (as indicated above) `by manualadjustment of the member |02 (Figs. 5 and 11) which controls |25 ismoved to and maintained in its raised position (Fig. 8) so that the oilis by-passed through the pipes |3| and |32 back to the tank |06, whilepressure is held in the pipes |2| and |23 by the check valve |39 and bythe valve |26 in which the piston' |34 is in its raised position (Fig.10) thus blocking the escape of oil to the pipe |35. After a period oftime which may be predetermined (although it may be terminated at thewill of the operator), the valve piston |3| 'in valve |26 moves to itslowered position (Fig. 9) thereby connecting pipe |2| with pipe |35whereby the pressure instantly drops substantially to zero and the oilmay return through the pipe |32 to the tank |06. This movement of valvepiston |26 terminates stage 3 and initiates stage 4. j

It will be noted that, in this stage 4, both valves |25, 26 have theirvalve pistons so pol sitioned that oil may iiow freely through them andthrough pipes |2| and |35 to the return pipe |32 back to the tank- |06.which comes at the end of the pressure applying operation correspondsalso to stage 1, except that the pressure inthe press cylinders isapproximately at zero. Another difference is that, in stage 4 after therelease of pressure in the hydraulic circuit, the upper platen' 10 ismoved upwardly so that the treatedpiece of work may be readily removedand another piece On the otherhand, stage 1 begins with the lowering ofthe platen 18 to engage a piece of work on the lower platen 13,

afterwhich pressure is built up back of the lower platen to treat thework piece to a pressure operation.

This stage 4 result that the shaft 18 is frictionally locked There are`provided in the hydraulic circuit, through suitable connections to apipe |16, which is a branch from the pipe |2I, two pressure governors Pand Q. Conveniently. governor P may have a working range between 63 and`470 tons pressure at the platens of the press or from about 410 lbs. toabout 3000 lbs. per square inch. Governor Q has a minimum cut-in ofabout 110 lbs. per square inch and a maximum of about 400 lbs. persquare inch. the range being from about 17 tons to about 611/2 tons atthe platens. The figures given above may be reconciled when it isunderstood that the pistons in the illustrated press are 14 inches indiameter and the platens are 26 by 54 inches. Since governor Q operatesto terminate pressing operations at a lowerrange than governor P, bothgovernors may be con- .nected to the pipe |18, and hence to pipe |2|,

With reference to Fig. 14 it will be observed that the clutch 16comprises annular clutch plates 200 keyed to the hub of thev drivingpulley rotatably mounted on the shaft 18. Keyed to the shaft 18 is asleeve member 202 having integral therewith an annular flange 204.Surrounding the sleeve member 202 inside the ange 204 is an annulararmature member 206 having a screw threaded periphery `for engagementwith a screw threaded surface at 208 on an enclosing annular cup member2|0, the latter being constructed and arranged to enclose the flange 204to which it is splined and to enclose the clutch plates or rings 200 andalso other annular clutch plates 2|2 which are keyed to the inside ofthe cup member 2|0. These clutch -plates 2|2 are shown as made of ber,although they may be of metal with fiber faces, which present frictionalsurfaces for engagement with the clutch plates 200. Upon energizing theclutch coils one of which is indicated at 2|4 (in magnet bodyl 2|5 keyedto the sleeve 202) the armature member 206' is pulled to the left inFig. 14 with the result that the clutch plates 200, 2|2 are firmlyengaged with each other to clutch thepulley 15to the shaft through the'sleeve 202. Upon deenergizing thecoils, the clutch is released by reasonof the movement of the armature 206 and parts attached thereto to theright in Fig. 14 through expansion of a number of light springs one ofwhich is'shown at 2|6.

The brake 11 comprises a member 220 which is attached to the machineframe, the member 220 having keyed thereto a plurality of annularfriction plates 222, these friction plates being shown as made of fiberthroughout, although they may be of metal having ber faces. In betweenthe members 222, are lannular plates 224 which are .keyed to a sleeve226 in turn keyed to the sleeve the springs 230, an annular armaturemember 232 is pressed toward the leftfin Fig. 14 thereby I `compressingall" of. the platesl 2212. 224 with the against movement by the brakemembers in the brake device 11. Upon energizing the brake coils one ofwhich is shown at 234 with a coil shield 235 between it and the armature232, the latter is drawn to the right in Fig. 14, thus releasing thepressure on the brake plates 222, 224, whereby the brake is disengagedfrom the shaft. At 238 are shown collector rings of the electricalmechanism, the rings being insulated from the magnet body 2|5 whichcarries the clutch and brake coils. Incidentally, brake and clutchadjustment may 'be secured through proper setting of the threadedmembers 228 and 206, respectively.

It will be clear that, upon energizing the brake coils the brake isdisengaged with respect to the shaft 1 8 while, upon energizing theclutch coils,

the clutch is caused to engage to hold the pulley 15 in. drivingengagement with respect to the shaft 18. This isthe normal operation ofthe clutch and brake since, in most press operations, the clutch will beengaged and the brake disengaged while a platen is being movedmechanically toward the other platen. On the contrary, the clutch isdisengaged and the brake engaged when the platen is in its open positionor when it is in pressing relation with respect to the other platenduring building up of pressure in a pressing operation. Sometimes,however, both clutch and brake are disengaged thereby permitting theupper platen in the illustrated machine to swing -to open positionwithout any driving action on tions of the clutch and brake devices willbe described more in detail later in this specification.

Control of the press is exercised through a` number of manually operablemembers having electrical connections to the` power means for causingrelative movement between the upper and lower platens of the press,means being also provided for exercising automatic control of valves inthe hydraulic circuit whereby the lengths of time that the leather -issubjected to heating at substantially zero pressure and subsequently atmaximum pressure may be predetermined. The control referred to isexercised through electrical circuits including various relay switches,time relays, clutch and brake contactors, solenoid contactors, andpressure governors, all obtainable in the open market as well-knownelectrical units. These latter are shown in Fig. 16 enclosed inrectangular spaces deflned by dash lines. Upon energized by completingcircuits to the otherv side of the supply line.

In order to prepare the press for operation, a

. main switch |40 (Fig. 16) is closed. At this time a limit switch X isoperative by reason of the. fact that a cam |56 4on the shaft 82 of thepress was left in a positionl to close contacts XI and X2 in limitswitch X, at the end of the preceding cycle of operations. Closing ofthe main switch |40, therefore, results in energizing the coil of anon-repeat relay A whereby contacts A2, A3 and A4 in relay A are closedand contact Al opened. 'I'he current energizing relay A may be tracedlthrough thecoil in relay A, through normally closed contact W3 in afoot switch W, adapted to be operated by treadle |51 TFig. 1), thencethrough contact X2 and normally closed contact V| in an emergency buttonV. It will be'noted that the closing of contact A4 establishes anelectric interlock (through A4 and normally closed contact H3 inarelay'I-I to be described later) i. e.. a shunt circuit around contactW3 in the foot switch W. Hence, depressing the treadle |51 and openingcontact W3 does not break` the Acurrent energizing the relay A.

In order to initiate the closing of the press, the foot switch W (Fig.16) is closed by means of the treadle |51 whereby contacts W2 and W4 inswitch W close while WI and W3 open. Closing of contact W4 establishes acurrent through the coil of master relay D (thence through W4, A3, XIand VI) and thus energizes master. relay D whose contacts D| and D2close simultaneously. The closing of contact D2 in turn energiZes thecoil in a brake contactor B, whose contacts BI, B2 and B3 are thusclosed, while through the closed contacts DI and Bl the coil in a clutchcontacter C is energized, closing contacts CI and C2. Thus, the coils ofclutch and brake are simultaneously energized whereby the brake isdisengaged and the clutch engaged, the crank shaft 82 of the pressbegins to rotate and the press arms begin to close. Inasmuch as thecurrent energizing the clutch contactor C is dependent on the closing ofswitch Bi it can be Vseen that the clutch cannot be energized, i. e.,

,through the clutch and brake magnets.

Shortly after the upper platen of the press has begun its downwardmotion, a contact Z2 in a second limit switch Z opens while contact ZI-closes. This is due to the rotation of a cam |64 mounted on shaft 82. Atiming diagram (Fig. 6) shows the open positions in dotted circles andclosed positions in heavy lines of the contacts of the variouscam-operated limitl switches. The vertical center line in Fig. 6represents the crank shaft dead center positions for the fully open andfully closed press platen. During almost the full downward motion of thepress platen (as seen in Fig. 6) contact ZI remains closed and iseiective to hold the brake contacter B energized, i. e., theY brakedisconnected independently of masterrelay- D. It is to be understoodthat the operator is required to hold the foot switch. |51 depresseduntil the closing of the press has been completed. Should the footswitch be prematurely` released, the current through W4 energizing themaster relay D would be interrupted and the clutch disengaged. However,the brake coil would be held energized, with the brake disen- .gagedthrough theaction of contact ZI, and the crank shaft would be free torotate. The rocker arms 1| of the press are unbalanced, that is, soweighted as to return the upper platen of the press to'open position, ifthere is no driving or breaking power on the crank shaft. Thus theoperator is able, in an emergency, not only to stop the closing of thepress immediately but also to obtain opening of the press by the simpleexpedient of removing his foot from the treadle |51.

- limit switch Y are closed by the action of a cam |53 also mounted onshaft 82.l The closing of -contact Y2 is immediately effective toenergize thecoil in a timing relay N and to start a synis returned tonormal with contact ZI open and Z2 closed. At exactly dead center,contact XI and X2 in limit switch X open whereby relays A and D aredeenergized, theA opening of contacts DI and D2, of course, drops outrelays C and B,

. through E3, F5, M4 and Y2.

chronous motor N5 therein running. A tap 'on 75 deenergi'zing clutch andbrake coils. The clutch is released, the brake becomes effective throughspring pressure, and the press stops in closed position. The foottreadle |51 may now be released, returning all contacts in foot switch Wto normal, as shown in Fig. 16.

Contact A| having returned to closed position upon deenergizing the'coilin relay A, contact WI, which closes when the foot switch is released,.becomes effective to energize the `coil in a repeating relay H whichcauses contacts HI, H2, H4l and H5 to close and contact H3 to open. Withthe closing of contact HI an interlock or shunt circuit around Al and W|is established holding the coil in relay H energized, regardless of apossible redepression of foot treadle |51, that is, opening of contactWI. Current may be traced through coil in H thence either through A| andWI in sequence or through HI, thence The purpose of establishing thiscurrent through repeating relay H will be described later.

The time relay N, of course, has remained energized and after thetiming' motor N5 has counted of! the time period for which the relay hadbeen set contact Nl' opens, stopping motor N5 and contact N3 closes,energizing solenoid contactor K by current through the coil of contacterK, and thence' through N3, GI, E3, F5, M4 and Y2. This causes thecontacts KI and K2 in the 'contactorK to close, energizing the solenoid|23 which in turn raises piston |34 in the valve |25 thus closing thelatter and causing the building up of pressure in the system, asheretofore explained.

In addition to being ame to adjust the amountv of time required foroperation of time relay N, it is possible to eliminate the time dwellaltogether by manual closing of the contacts RI and R2 in a selectorswitch R. Fig. 16 shows clearly that contact RI of the selector switch-Rprovides a shunt circuit around the delayed contact N3 of the time relayN, thus allowing the coil in contactor K and the solenoid |23 to becomeenergized immediately uponcl'osing of the contacts in the limit switchY. Thus, valve |26 closes before the press platen4 reaches the fullextent of its downward motion, .thus permitting the Jumping of pressure,as previously explained'in connection lwith the lregulating valve |31.As heretofore stated, the closing of valve |26 (either previous to thecompleted closing of the press or after a period of dwell) causes thepressure to rise in the press cylinders 86 and the rate of building upsuch pressure is deternined by the manual stroke adjustment ofthe pumpli(assuming a constant speed of the pump) and not by any element of theelectrical circuit. When the hydraulic pressure-being built u P3 willmake contact with a' high contact Hi (as to maintain the valve |25 intheby-passing position oi Fig. 8. s

Should pressure in the press cylinders 36 fall very substantially, dueto the said leakage, the

Lo contact (shown in full lines) within the presaround the coil of thepressure governor. De-Iv shown in dotted lines), which is adjustable todetermine the pressure (withinethe range oi! ,pressures givenl above) atwhich the pressure governor cuts in to allow current to flow through therelay coil of the pressure governo sure governor P will be established,in which case the coil of the pressure governor is deenergized,

since the circuit established by the new position of the contact memberP3 is a shortcircuit energizing of the coil in the pressure governor P`opens all oi the contacts therein and alsoin the control relay F and inthe solenoid contacter L. y

vthe result being that the solenoid operated valve l5 piston |30 dropsto its `lower or rest position) (Fig.

This current may be traced through the resist-V ance member P4 andthrough the coil of pressure governor P, thence through contact memberP3, contacting point Hi and contact YI in limit switch Y. Uponenergizing the coil in P, contaets Pl' and P2 cibse, Pl forming aninterlock.

through establishing a shunt circuit aroundl member P3, thereby to holdthe pressure governor energized whether or not the contact member P3maintains contact at Hi. Closing of contact P2 results in energizing thecoil in a control relay F, thus closing contacts FI, F2, F3 and F4 andat the'same time opening'contact F5. At this .time only two of thecontacts will be described, viz., Fi. and F4. Closingof contact F4energizes the coil in a second solenoid contactor L. (current throughcoil of contacter L, GI, E3, M4, Y2), whereby contacts L| and L2 in thecontactor L are closed, energizing the solenoid-coil 7) and once moreoperates to direct the pressure medium into the pipes |2| and |23 tobuild up the pressure therin and in the cylinders 53. 'I'his cycle ofpressure loss and rebuilding may or may not take place one or moretimes. The

Lo contact is manually adjustable as is the Hi contact, and the two maybe brought close enough together to provide a differential oi about 70pounds per square inch on the pistons, thereby providing fora drop ofabout ten tons in the pressure on the work piece before pressure be- Agins tobuild up again. Whenvthe maximum pressure has been reestablished,the pivoted switch member P3 reaches Hi position in Athe ,30 pressuregovernor P which again operates determine the period during whichmaximum |21. Energizing of this coil results in lifting the ing up andmaintaining the maximum pressure.

This time relay M is energized and its timing motor started runningthrough the contact FI in control relay F. As in the mst-mentioned timerelay N, here again a tap is provided on the coil oi' relay M toprovide, through a normally closed contact MI, current for timing motorM5; from there and from the coil in relay M the circuit continuesthrough contact FI in control relayF and YI in limit switch Y.Immediately upon en-` 65 -pressure shall be applied to the leather.

When the timing motor M5 in the time relay 40 M3 closes and M4 opens.The opening of contact M4 causes solenoid contactors K and L to bedeenergized, thereby allowing'the valve pistons in both valves |25 and|26 to drop, thus instantly releasing the built-up pressure in the cylainders 86 and reestablishing the normal iiowof thepressure mediumthrough pipes |20, |2| and back through pipes |35 and |32 (Fig. 12).Closing ofv contact M3 establishes-a circuit through the coil of `masterrelay D through said contact 5 Ma and through contact Y2 1n limit switchY,

ergizing the 'coil in time relay M, an interlock 'contact M2 closesproviding a shunt circuit around Fl' and thus `holding relay M energizeduntil the current supplied to it is broken by the opening of Y| in thelimit switch Y. The delayed In case there should be leakage of pressuremedium past valve piston |34 in -valve |28 (Fig. 12) during the timedwell of time relay M, while Y the maximum pressure is being -held inthe press contacts Mi, M3 and M4 will operate after the timing motor M5has completed its preset cycle.

at PI in the pressure governor is still effective to energize the coiltherein. whereby the pressure governor through its contact P2 remainseil'ective thus energizing the master relay D and, in the mannerpreviously described, making the brake inoperative and the clutchoperative whereby rotation of the crank shaft to open the press arms iseffected. The opening of contact M4 at the same timecauses thepreviously mentioned repeating relay H to become deenergized when thepress begins to open. Near the end of the movement of the upper platento its uppermost posicomeenergized because W3 will then be in openposition, and the press cannot be started again until after W3 has beenclosed again through releasing the foot switch to establish thedescribed l current through relay coil A.

At the end of the upward movement' of the tion, the cam |56 again closeslimit switch X.,

upperplaten the camy |63 opens the limitswitch Y, thus deenergizing thecoil in master relay D,

'l5 .hence dropping out clutch and'brake contactors C and B with theresult that the brake is on, the clutchofi', the presses stopped in openposition and ready for another cycle.

The time dwell at maximum pressure, controlled by timing motor in relayM is adjustable within the range of the instrument. It is to beunderstood that both time relays N and M can be commercially procuredhaving a rangeV of from 4 to 40 seconds in two-second intervals. beunderstood also that instruments of a different range may be substitutedtherefor, for instance, one commercial timer being operated by a vacuumtube rather than by a synchronous timing motor and having a range offrom .6 to 12 seconds, in a stepless adjustment.

I have provided means to eliminate :either or both time dwells at thechoice of the operator, the time dwell at substantially zero pressurebeing eliminated, as previously described, through closing of .selectorswitch R. Another selector switch T has been provided having twocontacts TI and T2 which are open when the time dwell is desired and athird contact T3 which is closed in this case. If these three contactsare reversedr they will make effective the three contacts F2, F3.

and F5, respectively, in control relay F. In this case the operation ofthe press will be .as described heretofore up to the point where themaximum pressure has been reached and the contact member P3v andpressure governor P makes contact at the Hi point energizing relay P,whereupon contact P2 serves to energize the coil in relay F. The contactTI in the selector switch T being closed, it forms together with contactF2 in the control relay F an interlock for the latter through ,theestablishment of a shunt circuit around contact P2 thus making controlrelay Fr independent of the pressure governor and holding it energizeduntil the press has opened at which point opening of contact Yidisconnects coil of relay F. The relay F which, in this case is used tocontrol the opening of the press and also to relieve lthe pressure inthe hydraulic system, thus replaces contacts M3 and M4 in the maximumpressure time relay M which performed these functions as previouslydescribed when a time dwell was warranted. To effect the opening of thepress, the master relay D is energized by a current flowing through thecoil of this relay,

through contact T2 in the selector switch T and.-

at .maximum pressure.

In kiss-plating operations, the press is organiz'ed to apply a heatedplaten for a short time and under low pressure to the grain surface ofrelatively low grade skins and to boarded skins of various grades. Insuch operations, the skins are treated to a heated platen .during thetime that it takes to build up the pressure to 25 or 30 tons, for.instance, (the`range being up-to about 60 tons) whereas embossingoperations normally involve pressures at about 400 tons and even higher,i. e., at about 2500 lbs. or more per square inch, while s'rnoothplating might bedone at pres- Itis tof For kiss-plating, therefore, itis desirable to'operate the press rapidly and this may be convenientlyaccomplished by arranging the power` control mechanism in such mannerthat the press continues to operate cycle after cycle once the operationhas been initiated. Besides a pressure governor P, operative in a rangeof about 63 to 470 tons, there is provided a low pressure gov'- errior Qoperative at pressures in a range of about 17 to 62 tons. As indicatedin Fig. 12, a threeway valve |88 is provided to connect or disconnectpressure governor Q with respect to the main line |2| of the hydrauliccircuit.

vus

It will be noted that for-operating the press in the kiss-platingtreatment of skins, the selector switch R is set so as to eliminate thetime dwell at' substantially zero pressure. However,

the selector switch .T- may remain set at either of its' two positionssince the time delay at maximum pressure is automatically eliminated bythe use of the low pressure governor Q, it being obvious that, with bothpressure governors connected to the pipe |2l, pressure in the said pipe|2| will never rise above the maximum of the low pressure governor Q.

The operation of the press organized for kissplating operations beginsin the same manner as explained above for the usual smooth platingoperation. Upon depressing the -treaclle |51 by which switch W4 in footswitch W is closed, the upper platen begins to close, and Shortly beforeit has reached fully closedV` position the limit switch Y will close,energizing the solenoid contactor K with the result that the valve |26(Fig.

l2) closes and pressure begins t0 build up in the pipe |2| and in thepiston cylinders 86. This pressure will act on both pressure governors Pand Q. However, since pressure governor Q has a lower operating rangethan the pressure govemor P, a pivoted contact member Q3 (Fig. 16) inthe pressure governor Q will reach its Hi contact before thecorresponding contact Amember in pressure governor P becomes effective.When contact member Q3 reaches Hi position, the coil in the pressuregovernor-Q will become energized vwith the result that both contacts QIand Q2 are moved to closed position.

causing the coil therein to remain energized even after the pivotedcontact member Q3 leaves the Hi contact. 'I'he other switch Q2 allowsthe coil in a second control relay G tobecome ener.- gized. 'I'hecontrol relay G has, for the kissplating cycle, the same function as thecontrol relay F in the press organized to provide instantaneous openingof the press at maximum pressure, as before described. An electricinterlock for holding control relay G energized during the openingstroke of the press has been provided by removing from the pressuregovernor Q the connecting wire between the upper end of the coil and theLo contact. This connecting wire is normally furnished in commercialinstrument, as shown in pressure governor P. In the absence of suchconnecting wire in the pressure governor Q there is no short circuitingaround its coil when the pressure drops low enough in the pressuregovernor to allow contact device Q3 to make consures ranging from aboutto perhaps 300 tons. 75

tact at Lo. Hence, the coil in Q remains enernormally op'en contact G2which, upon closing, establishes'current through the coi1 of masterrelay D, through contact .G2 and limit switch contact Y2 to energize theclutch and brake coils and thereby effect the opening of the press. Atthe same time normally closed contacts Gl and G3 open. The function ofthe latter will be described later. The function of the opening or GI isto deenergize the solenoid contactor K whereby valve |28 is opened andthe built-up pressure in the hydraulic system immediately releasedthrough pipes |35 and |32 (FigflZ).

It will be noted that this same function was performed in the smoothplating or embossing operation of the press by either contact F5 in thecontrol relay F or contact M4 and time relay M. However, either oi thelast-named contacts performed the additional function of interruptingthe current through the coil of repeating relay H. While in thekiss-plating operation, GI serves to relieve the hydraulic pressure, itis so positioned that it will not interrupt the current which holdsrepeating relay H energized, and which, irrespective of the operation oiGl, may

lstill be traced through coil of relay H, contacts HI, E3, F5, M4, andlimit switch contact Y2. Re-

peating relay H has been energized, as previously described, through therelease ofthe foot treadle |51 by which contact WI of the foot switchwas closed. If the foot switch now remains released relay H will remainenergized until the press has fully opened. Shortly before the openingof the press is completed, limit switch contacts XI and Y2 close againand X2 energizes the coil of relay A through the closed foot switchcontact W3, ,A through limit switch contact X2 and contact V| in theemergency switch V. ContactXl of the limit switch at the same timeserves to hold the repeating relay H energized by current which owsthrough the coil of relay H, relay contacts `H4 and- A2 (the latterclosed when relay A was energized) selector switch contact R2 and duringthe press will open and stop in its openingposition. After this a newcycle of continuous operations may be initiated by holding the treadledepressed for one closing stroke of the press as described above, andthen releasing it.

In kiss-plating operations the depression of the foot treadle toterminate the operation would probably. take place during the openingstroke. It will be remembered that repeatingrelay H remained energizedwhile the press was opening and also during the closing stroke and hencethat. al contact H2 in said relay Hremains closed. If, during theopening stroke, the foot treadle is depressed, closing the contact W2 inthe foot switch W, a current will beffestablished energizing the coilofan emergency relay E and l flowing successively through W2, H2, F5, M4

- and Y2.

through contacts XI and Vl. Thus it can be seen y that the repeatingrelay H will remain energized not only during the opening stroke of thepress but also during the immediately following closing stroke, that is,until limit switch X opens again.

The closing of the press-follows immediately upon its opening withouteven `releasing the clutch or energizing the brake because a contact H5in repeating relay H has become closed and serves to hold the masterrelay D energized even after limit switch Y2 has opened upon reachingFig-.16 that contact H5 is arranged in parallel with contact W4 of thefoot switch which latter serves to operate the master relay D in thesmooth plating or embossing operation. In these previously describedoperations, however, repeating relay H had been dropped out previouslythrough the opening of either contact F5 or M4,

while in the kiss-plating operation relay H has remained energized'during the opening stroke of the pressand remains so again during theclosing stroke.

- limit switch Z, thus allowing the press arms to l From this point on,the press'will continue cycle `after cycle, closing, building up thepressure to. the high point Hi on the pressure governor Q, opening andimmediately closing again, and so on, until the operator stops it by asecond depression' of the foot treadle. This redepres-v sion of the foottreadle |51 may take place at any time, that is, during the down strokeof the press, during the building up of pressure, or

The relay E, in addition to an emergency function t be described later,serves to stop the continuous operation of the press by the opening ofits contact E3 vwhich interrupts the current owing through the coil ofrepeating relay` H. It should be mentioned that an interlock is providedfor relay E by means of a current owing through the coil of relay E, acontact E2 therein, and through limit switch contact YI. Thus even ifthe footswitch is only` momentarily depressed the relay Ewill remainenergized until the press has opened completely and the l now opencontactA E3 will prevent the repeating relay H from becomingenergizedagain. Upon closing of limit'switch X `near the high positionof the upper press platen, the current through relay H does not becomereestablished since the contact H4 in said relay H has opened with thedeenergizing of relay H and will not close unless relay H is energizedby means of contacts AI and WI. This means then th'at the press willstop in its fully open position since contact H4 (used to energizemaster relayvD) remains open anda new cycle of operations would have tobe started again in the manner described above.

Should the depression of the foot switch, in-

I tended to stop the continuous operation of the press, occur after thepress h as opened and immediatelystarted on its down stroke, then therelay E -will not become effective but even then the press/operationwill be interrupted immediately. This is due to thev opening of switchcontact W3 when the foot, treadle is depressed.

At this time the function of contact, H3 in thel leased while, as hasbeen shown previously, the e brake coil is held energized (thatis, withthe brake on) by the action of contact ZI in the swing back to theiropenl position by means of gravity. In consequence of .deenergizingrelay A, contact A2 has also opened, interruptingthe current throughrepeating relay H so that the press will not start again after it hasbeen returned to open position, as described, or after the the openingof the press, and in each case of the press, the foot switch isdepressed while the press is closed andthe pressure being built,

up, the coil of relay E is energized, as described above. In this case,lin 'addition to contact El opening, whereby the repeating relay H isdropped out, the relay A effects immediate opening of the press, butthis is an emergency Operation and will be considered later.

If the manually operable selector switch R.V

should be set to the open position, as shown'in Fig. 15, therebyproviding the time dwell at subncras the usual cycle of the pressorganized for smooth plating or embossing wherein the foot switch phasto be released and then again depressed in order to secure successiveoperations l .of the press.

It -is believed that for certain types of leather or small size skinskiss-plating may be accomplished satisfactorily with pressures no higherthan, perhaps, about v15 tons which may be securedrfor instance, by theso-called jumping of pressure, that is, by the depression of thefloating vpress pistons li due to the action of the downwardly movingupper platen. If this is so. then noA building up of ,pressure beyondthat reachedby jumping" is necessary and for this type of leather thecrank shaft may be kept ro- `tating continuously, the clutch neverbecoming deenergized, that is, released, either in the open or closedposition of the press. As has been pointed out previously,v the amountof jump" pressure reached may be manually adjusted by regulating thepressure of spring |41 (Fig. 1l) in back pressure'valve |31-(Flgs. 11and 12). 'I his methodof operation may be secured by the manual clomngof a selector switch S. As will be seen from Fig. 16, this'switch S isso arranged as to allow control relay. G to become energized .Y thefirst time, that. is, the pressure rises to the upon/the closing of acontact Z2 in limit switch z which, by reference to mfc, sin be round tooccur practically at fully closed position of the prs but having a veryslight overlap with the blosedposition of limit switch X This enablesthe control relay Gato become energized just before the clutch would bereleased and the brake applied in the press closed position and withoutwaiting for pressure to bebuilt up in the pressure governor Q; Controlrelay G, of course,

energizes master relay D as in the previously described kiss-platingcycle, (where the pressure was built up in the pressure governor Q)[with the. result thatbrake and clutch coils remain energized, that is,the clutch is never released nor the brake applied, and the crank shaftcontinues right through its dead center position to effect the immediateopening of the press. Reference to Fig; 6 shows'that Y2 closed enoughahead or the crank shaft reaching itstottom.

dead center to allowthe valve\piston l in valve 26toclose atapointwherethe pressarms would still have a small amount of travel be; forereaching their lowest position so that, due

to the action of the press arms on the floating rams, a dennite pressure(jump." pressure) will be produced' before valve, |26 again opens underthe influence of opening contact GI of thev control relay; this latter,of course, takes place at 7 6 means 'are applied to crank shaft, un-

the point where contact Z2 closes. At the same moment G2 also closes andsince this occursjust before Xl opens, the coil of master relay D isnever allowed to become deenergized, thus holding the clutch on and thebrake oif' continuously. In all other respects this kiss-plating opez-,ation with jump pressure functions exactly like the before-describedkiss-plating operation with built-up pressure, the repeating relay Hbeing energized and remaining energized through the opening and closingstrokes of the press as closing the preadjusted pressure buildup with orwithout time dwells takes place and then the press opens and stops inposition. To initiate a second cycle the treadle must first be releasedand then depressed again.

A second mode of operation may be chosen by reverse setting of yvalve|88 to cut in pressure governor Q, in which case the pressure range willbe from zero to 62 tons, whereof a' range o f from about Q to about 15tons may be obtained by the previously described jump" pressure whilethe remainder of the range from about 16 to 62 tons is determined by thesetting of pressure governor Q. In the last-mentioned pressure ranges,it is impossible to obtain a time dwell at maximum pressure. Theoperation of the press in this case is what is commonly termed fullautomatic after the press has been closed for predetermined point, thepress opens and-immediately begins closing again withoutinterruption,.the operator being allowed just enough time to shift'askinto a new pressing Position between the platens or to remove itpreparatory to introducing a new skin. Of course. the operator hascontrol over this immediate reclosing of the press since to stop thepress all that is required is a depression of foot treadle |61 at anytime during the full automatic cycle. It is believed that in the lowerpressure rangesa I time dwell at substantially zero pressure is notrequired. However, provision has been made for obtaining it by means ofselector switch R. The choice of this time dwell atl substantially zeropressure automatically precludes full automatic operation of the pressand changes the cycle to a semi-automatic one the same as is obtainedwhen `working in the high pressure range above 63 tons.

.certain safety features for the Aprotection ofv the operatonas well asfor the protection of the press itself or the leather to be treated, arein corporated inthe illustrated embodiment of the invention. f For theprotection of the operator, means 'is provided for interrupting thelclosing stroke of the press platen at any time, at the samevtime-returning the upper movable .Platen to its fully open position. Itis to be understood that, in theillustrated press construction, the

arrangementis such that, if no or brak- .may be operiited at balance ofthe prese arms will swing them into fully open vposition from a closedposition -or from one approaching closed position. This constructinalfeature is made use of in the electrical safety controls hereinprovided. At any point during the semi-automatic closing stroke of thepress arms, i. e. when working in the high pressure range, or during theinitial closing in the pressure range up to 62 tons, the operator hastwoindividual means for interrupting this closing stroke. He may releasethe foot switch by withdrawing his foot from the treadle |51 ,and thus:interrupt the current through the master relay D because of the openingof contact W4 in footswitch W. Alternatively, he may depress theemergency button V which interrupts the same current by opening contactVI in said button V. Opening of the master relay D, of course,deenergized the clutch while the brake is held energized (disengaged) bymeans of con-4 tact ZI in limit switch Z, as previously described,allowing the press arms to be returned to their open position bygravity. As said just above, this emergency opening is accomplished bydepression of the emergency button as well as by release of the footswitch. In either case, the press will remain in'its open position untiltheA foot switch has been yreleased and then redepressed to initiate arepetition of the normal cycle.

In connection with thepperation of the press within the low pressurerange up to 62 tons and performing the full automatic continuous cycle,it has been explained that depressing the foot treadle while the pressis running continuously will terminate the'operation of the press and ifthis occurs during the down stroke of the upper platen, the currentthrough master relay D will be interrupted through the opening ofcontact A3,`nonrepeat relay A having been dropped out opening ofemergency button contact VI whichk at the same time interruptsv the.current supply to master relay D as well as repeating relay H. Thus,depression of the emergency button V during the full automatic closingof the press arms has the same eiect as operation of foot ,switch W bymeans of depressing treadle |51, namely,

to interrupt the closing of theC press and permitV` thepress arms toreturn to open position by gravity and stop there until a new cycle isinitiated in the usual manner.

In addition, another safety feature is provided making it possible tocause instant opening of the press at any time after its closing hasbeen completed, for instance, during the building up 0f pressure orduring the' time dwells. It has been shown previously that after thepress arms stopped in their closed position relay A was deenergized,closing contact AI thereof; and, if now the foot switch |51 werereleased, repeating relay H became energized through the closing of footswitch contact WI, whereafter H remained energized by means of theinterlocking contact H| Energizing relay H closed a contact H2 and theoperator can now, in case of emergency, by depressing foot treadle |5l,and consequently closing foot switch W2, establish a current through thecoil of emergency relay A, thence through W2, H2, F5, M4 and Y2. Thisis, of course, true for either the semi-automatic orthe full automaticcycleof operation because in either cycle repeatingl relay H becomesenergized by the release of the foot switch after the press is closed.As has been previously pointed out, in the fullautomatic cycle, thisrelay H usually remains energized while in the semi- .automatic cycle(that ls, within the high pressure range) it is dropped out again by theopening of to the emergency depression of the foot treadle,

is immediately released bythe opening of valve |26 (Fig. 12)'. ContactE4 of the emergency relay at the same time establishes a current throughmaster relaycoil D by way of E4 and Y2, thus starting the immediateopening of the press in a manner exactly like the action of eithercontacts M3 on the time relay M, G2 in control relay G or F3 in controlrelay F (together with switch contact T2), had the press been. allowedto continue its normal cycle.

If the treadle |51 is held depressed until after the completed openingof the press arms, the non-repeat relay A will not again become`energized upon closing of limit switch F2, thus making it impossiblefor the crank shaft to continue its rotation after the press is open.The foot treadle must rst be released (allowing relay A to be- Fig. 16shows that a contact- V2 `in the emer gency button V is arranged inparallel with the combined contacts W2 and H2, by the closing.

of both of which the emergency relay E became energized. Thus not onlythe foot switch but also the emergency button may be used to energizeemergency relay E by means of a current through the coil'of Ethrough-V2, F5, M4 and Y2. It is clear then. that after the press hascompleted the closing stroke and at any time thereafter until it againbegins to open, the action of the press may be immediately interrupted,the pressure of the hydraulic medium relieved, and the press armsvopened either by'a depression of the emergency button or by a newdepression of the treadle which had been released subsequently to theclosing of the press'.

In order to prevent an operator from shortening the time of dwellatmaximum pressure .or from working the leather at insuilicient pressureby means of the above-described emergency devices, provision hasbeenmade to sound a gong |92 or other indicating device every time thepress is opened before completing its normal cycle, so that anyrepetition of this emergency opening will be called to the attention ofthe supervisor. Current is supplied to this gong |92 througha smalltransformer J which, in turn, is energized upon operation of theemergency relayE by a current which passes through the /primarytransformer coil, thence through contact vEl and normally closed contactG3 in control relay G and thence through a selector switch U t 'It willvbe noted that when operating in the through the coil of relay E, whichis normally established by closing of emergency contact V2 or'footswitch contact W2, is then interrupted either at the contact F5 orcontact M4 of the control relay F or time relay M, respectively,

either of which has been operated to start theL opening of the press.Thus, the emergency relay E has been rendered inoperative when openingof the press arms started, and'hence if the emergency button is operatedafter that time the gong will not ring. In other words, the emergencyrelay E can become ener-gized and cause the gong or signaling devices192 to sound only if the emergency button is operated after the presshas closed and before the press begins its opening stroke. `This ofcourse is the period yiuring which the` operator could shorten the 'timeof operation at the expense of the quality of the work if he were notinhibited by the ringas new and desire to secure by Letters Patentcontrolled by control relay G and if theemergency relay E is operated(either by means of foot treadle or emergency button) after the presshas started to open, that is, after relay G has become operative, thenormally closed contact G3 has opened (and remains open until the presshas stopped in the open position) thus interrupting the current supplyto the primary coil of transformer J. Therefore, in full automaticoperation also the gong will only sound if theemergency b-utton (or footswitch) is used during the time of building up pressure and not afterthe predetermined maximum pressure` has been reached and the press begunto open.

It has been possible to use presses, as heretofore constructed, in amanner which allowed the operator to vary the pressure built up duringeach pressing operation, according to his judgment. Such Ian operationof the Apress described in this specification is possible because thepress can (as described in connection with an emergency operation) beopened at the will of the operator at any time during the building up ofpressure. It is, of course, understood that the amount of pressureacting onk the upper platen at each instant may be read'from thepressure gage |24 incorporated into the pressure governor .P. When it isdesired to have the operator use his own judgment as to the amount ofpressure to be used in each pressing operation,

when plating or embossing hides or skins, the t0 sounding of the gongmay be prevented by opening the manually adjustable selector switch U inthe line supplying current to the transformer J. Ordinarily the switchU, along with both time relays M and N, as well as selector switches` R,S, and T, will be in a box which may be locked so that the foreman orsupervisor may decide the type of operation tobe performed by the press.The enclosing cases housing the adjustment members of the two. pressuregovernors are also provided with locks. Of course, the treadle |51controlling foot switch W and the emergency button V are alwaysaccessible to the operator.

Having descr-ibed my invention, what I claim -one of said platens beingmovable relatively to the other` and one of the platens having a heatedwork contactingsurface, mechanical means operative to cause relativemovement of the `platens, hydraulic means comprising a piston cylinderand a piston to move the movable platen toward the other platen, a lowrange pressure governor in the hydraulic circuit, a pump arranged to becontinuously operated to circulate a pressure medium through saidcircuit whereby a work piece engaged by both platensvis subjected toheat at a lowA pressure built up to a selected point under control ofsaid low range pressure governor, and electrical means including'saidpressure governor and comprising a manually operable member for securingoperation of both the mechanical and hydraulic means in timed relationto each other to effect rapidly repeated operations of the press in thefull automatic cycle.

2. In a press, an upper and 'a lower platen one of which is movable withrespect to the other to exert a pressure applying operation on a workpiece, mechanical means for moving one of the platens toward and fromthe other platen to open and close a gap between the platens, hydraulicmeans including a valve for operating one of said platens in a pressureapplying operation, electrical means for controlling the operation ofboth the mechanical means and the hydraulic means in timed relation toeach other, and la manually operable member having connections in saidelectrical means to initiate operationl of rboth the mechanical and the`hydraulic means, said electrical means comprising an electrical powerunit for said valve in the hydraulic?,

means and electrical controls for said mechanical means so arrangedthat, upon initiation of pressure applying operations by a singleoperation of the manually operable member the' press andl a manuallyoperable member having conl nections in said electrical means toinitiate operation of both the mechanical and the hydraulic means, saidelectrical m'ans lcomprising a solenoid contactor for said valve inthehydraulic means and controlling relays for said mechanical means soarranged that, upon initiation of pressure applying operations by asingle sustained operation of the manually operable mem'- ber for apredetermined'period in the ilrst pressure applying operation, the presscontinues in I full automatic cycle with repeated operations of thepress until control of the latter by the electrical means 'isinterrupted. y

4. In a press, a lower platen and an'upper platen movable toward andfrom each other, mechanical means for eiecting movement of one of saidplatens toward the other platen to close the gap between the platens,hydraulicmeans ens to effect a pressure applying operation, a

pressure governor connected to said hydraulic means, electrical meansincluding said pressure governor for opening said valve to terminate thebuilding up of pressure in the hydraulic means, said electrical meansserving also to control said mechanical means, and a manually operablemember having connections in said electrical means to initiate operationof both the mechanical means and the hydraulic means whereby saidmechanical, means is 'caused to move one platentoward and from theotherplaten and said hydraulic means is rendered operative to effect abuilding up of pressure between said upper and lower platens in timedrelation to ,the mechanical movement of one ofthem, and said electricalmeans including a repeating relay so connected as to secure repeatedoperation of the press in a full automatic cycle when said manuvallyoperable member is operated to initiate pressure applying operation.

5. In a press, an upper and a lower platen, me chanical means for movingone platen toward and from the other platen alternately to close and toopen a gap between -the platens, said means comprising a power shaft,clutch and brake devices for controlling operations of the shaft,hydraulic means including a valve for operating one of the platens toeiect a pressure applying operation, a pressure governor connected tosaid hydraulic ing a clutch contactor and a brake contactor respectivelyfor saidclutch and brake device, and a manually operable member havingconnections to said electrical means to initiate operation o'f the pressthrough both the mechanical means and the hydraulic means in timedrelation to each other such that one platen moves toward the otherplaten to cause both platens to engage a work piece resting on the lowerplaten, prior to the operation of said hydraulic means to eiect apressure applying operation during which pressure is built up in saidhydraulic means under control of said pressure governor, said electricalmeans comprising a repeating relay operative in said-electrical means.to maintain current in the clutch and brake contactors whereby theclutch remains on and the brake off to secure repeated operation of thepress in the full automatic cycle following a single movement of saidmanually means, electrical means including said pressure governor foropening said valve to terminate the building up of pressure in thehydraulic means, said electrical means having connections to effectoperation of the valve to cause building up of pressure in the hydraulicmeans and said electrical means including controlling means for saidclutch and brake devices, and a manually operable member havingconnections to said electrical means'to initiate operation of the pressthrough both the mechanical means and the hydraulic means in timedrelation to each other such that one platen moves toward theother'platen to cause engage'- following a single movement of saidmanually operable member for a predetermined period in the rst pressureapplying operation of thel press. 6. A press according to claim 5 inwhich a limit switch operating in timed relation. to said power operablemember to initiate a pressure applying operation of the press.

8. A press according to claim 7 in which a limit switch operating intimed relation to said power shaft maintained said repeating relaycontinuously operative to holdA a master relay in control of the clutchand brake contactors for full automatic operation of the press.

9. In a press, an upper platen, a lower platen, one of said platensbeing movable 'relatively to theother and -one of the platens having aheated Work contacting surface, mechanical means operative to causerelative movement of the platens,

hydraulic means comprising a piston cylinder and a piston 4to move themovable platen toward the other pl n in timed relation to the operationof said me hanical means, a low range pressureL governor in saidcircuit, a pump arranged to be r continuously operated to circulate apressure medium through said circuit, whereby a work piece engaged byboth platens is subjected toheat at a low pressure which is built up toa selected low pressure under control of said low range pres' suregovernor, electrical means including said pressure governor andcomprising a manually. operable member for vsecuring rapidly repeatedoperatlons of the press in the full automatic cycle, and means including'a regulating valve in the hydraulic circuit to maintain a predeterminedvminimum pressure against the piston associated shaft controls asolenoid contactor for said valve in the hydraulic means to start thebuilding up of pressure therein.

'7. In a press, an upper and a lower platen, mechanical mea-ns formoving one of said platens toward and from the other platen, said meansing a solenoid contactor to effect operation of the valve to causebuilding up of pressure in the hydraulic means and said electrical meansincludwith the movable platen, whereby a work piece engaged by bothplatens is-rst subjected to heat at a minimum pressure and also to` heatat a low pressure built up under control of the low range pressuregovernor.v

10. In a press, 'an upper platen, a lower platen movable in an upwarddirection toward the upper platen, one of the platens having a heatedwork contacting surface, hydraulic means comprising a piston cylinderand a piston to move said lower platen in an upward direction,mechanical means operable in timed relation to said hydraulic means tomove one of the platens to close the gap beltween tbe platens whereby awork piece on the lower platen is engaged by both platens, a pumparranged to be continuously operated `to-circulate a-'pressure mediumthrough said circuit, means including a regulating valve in saidhydraulic circuit operative to maintain in the piston cylinder apredetermined lminimum pressure such as will just float the piston andthe lower platen,

' whereby the lower platen will yield against said pressure in thepiston cylinder when the work piece is engaged by both platens, theeiect being also to produce an instantaneous or jump pressure of lowdegree-on the work piece, and means comrapidly repeated operations ofthe press in the Y* full automatic cycle.

:,built up to a predetermined degree substantially above theinstantaneous or jump pressure produced by the upper platen in pressingagainst the lower floating platen.

,12.'In' a press, an upper and a lower platen movable v with respect toeach other to exert a pressure 'applying operation upon a work piece,one of said platens having a heated work contacting surface, mechanicalmeans for moving one of the platens toward the other platen to causevboth platens to engage a work piece on the lower platen,l hydraulicmeans including a regulating valveand an electrically controlled valvefor operating the lower platen, a pump for supplying a pressure mediumto' said hydraulic means, saidV regulating valve operating to raise thepressure in the hydraulic means sufficiently to oat the lower platen, apressure governor in said hydraulic means, electrical means forcontrolling said mechanical means and said hydraulic means including theelectrically controlled valve in timed relation such that thelast-mentioned valve is closed before the platens engage the work pieceon the lower platen whereby the' pressure is jumped inthe hydrauliccircuit and then built up to apoint determined by the presprisingamanually operable member for securing a heated platen at small pressurefor a predetermined period of dwell to be followed by the building up ofpressure toa point satisfactory to thel operator who then trips thepress to terminateV the pressure applying operation.

17. In a press, an upper and a lower platen I movable with respect toeach other to exert a sure governor, a repeating relay in the saidelectrical controlling means, land a manually operable member in saidelectrical means and operable to initiate a pressure applying operationof thel press and thereafter repeated operations of the press in thefull automatic cycle.

13. A press according to claim 12 in which a time relay is included inthe electrical means to delay the operation of a valve in the hydraulicmeans thereby to provide a predetermined dwell at substantially zeropressure, during which pressure is not built up in the hydraulic means,cutting-in of the time 'delay relay being accompanied by elimination ofthe repeating relay from the said electrical means, whereby a work piecemay be subjected to treatment by a heated platen at minimum pressure fora predetermined time or dwell and then to a built-up pressure undercontrol of the pressure governor, in a press conpressure' applyingoperation on a work piece, mechanical means for moving one platen towardand from the other platen, said means comprising a. power shaft andclutch and brakedevices for controlling the shaft, hydraulic meansincluding a` valve for operating onev of the platens for a pressureapplying operation, electrical means for controlling the operation ofboth the mechanicallmeans and the hydraulic means in timed relation toeachother, a manually operable member having connections in saidelectrical means to initiate operation of both the mechanical and thehydraulic means, said electrical means comprising an electrical powerunit for operating said valve in the hydraulic means and also clutch andbrake contaotors for the clutch and brake devices, respectively,together with a controlling relay for the last-mentioned contactors, anda repeating relay in said electrical means, all so arranged that,uponinitiation of pressure applying operations by appropriate movementof the manually operable member, the press continues in full automaticcycle with repeated operationsof` the press until control of the latterby the electrical means is interrupted.

18. A press according to claim 17 in which a time relay ls included`inthe electrical means to delay the operation of a valve vin the hydraulicmeans thereby to provide a predetermined dwell at substantially zeropressure, during which pressure is not built up in the hydraulic means,cutting-in of the time delay relay being accompanied by elimination ofthe repeating relay from the said electrical means whereby .a work piecemay be subjected 'to treatment by a heated platen at little or nopressure in a press conditioned for the semi-automatic cycle followingeach operation ofsaid manually operable member.

' 19. A press according to claim 17 in which a selector switch isincluded in the electrical means to provide, if desired, a shunt circuitaround the ditioned ,for the semi-automatic cycle following eachoperation of said manually operable member.

14. A press according to claim 12 in which a selector switch is includedin the electrical means to provide, if desired, a shunt circuit aroundthe time relay thereby to eliminate the dwell at substantially zeropressureand concomitantly therewith to restore the said repeating relayand the full automatic cycle, the latter being secured through propermanipulation of said manually operable member.

15. A press according to claim 12 in which a pressure governor isincluded in both the hydraulic and electrical means and a second timerelay included in the electrical means to give adwell for apredetermined period at a pressure maximum determined by said pressuregovernor, in a pressv selector switch is included in the electricalmeans to eliminate, if desired, the' second time relay and therewith thetime dwell at maximum pressure, whereby a work piece may be treated t0time relay thereby to eliminate the 'dwell at substanti'ally zeropressure and concomitantly therewith to restore the said repeating relayand the full automatic cycle, the latter being secured throughfpropermanipulation of said. manually operable member. f

20. A press according to claim 17 in which a pressure governor isincluded in both the hydraulic and electrical means anda second timerelay `included in the electrical means to give a dwell for. apredetermined period at a pressure maximum determined by said pressuregovernor, in a press conditioned for the semi-automatic cycle. `21. Apress according to claim 17 in which a selector switch is included inthe electrical means to eliminate, if desired, the second time relay andtherewith the time dwell at maximum pressure, whereby a work piece maybe treated to termined period of dwell to be` followed by the buildingup of pressure to a point satisfactory to the operator who then ltripsthe press by suitablel manipulation of the manually operable member toterminate the pressure applying operation.

2,2. In -a press, an upper and a lower platen, one of said platens beingmovable with respect a piston cylinder and a piston therein for supfporting the lower platen in a floating condition, said hydraulic meansincluding a regulating valve and a valve operative to check the flowof'the pressure medium through a part of said hydraulic means wherebypressure will instantaneously develop in said part of the hydrauliccircuit and in thelpiston cylinder when the work piece is first engagedby both platens, this instantaneous or jump pressure between the platensbeing regulatable by adjustment of said regulating valve electricalmeans for controlling both the mechanical means and the hydraulic meansin timed relation to each other such that operation of the hydraulicmeans precedes engagement of the work piece by both platens, and amanually operable member to control said electrical' means so arrangedthat operation of the manually operable member is followed by operationof the press in the full automatic cycle during which thepress performsrepeated pressure applying operations upon a work piece or work piecesintroduced by the operator between said platens. i Y

23. A machine according to claim 22 in which the mechanical means formoving one of the platenscomprises a power shaft together withelectrically operated clutch and brake devicesa associated with theshaft, and in which a con-v trol relay energizes a master relay whichkeeps the clutch engaged and, the brake released throughout repeatedoperations of the press in full automaticcycle.

24. In a press, an upper and a lower platen movable withrespect to eachother to exert a pressure applying operation upon a workpiece supportedon the lower platen, mechanical means including a power shaft for movingthe upper platen toward the lower platen to engage a work piece on thelatter, a clutch device and a brake device for controlling said shaft,combinedl mechanical and hydraulic means including a piston cylinder anda piston therein for supporting the lower platen in a floatingcondition, said hydraulicA means including a valve operative to checkmomentarily the flow of the" pressure medium through a part of saidhydraulic means whereby pressure will develop in said part of thehydraulic circuit and in the piston cylinder when the upper'platenpresses thework piece against thevlower platen, whereby the work piecebe' tween the platens is subjected toa jump pressure, electrical meansfor controlling the operation of both the clutch and brake devices andthe valve in the hydraulic means in timed relation to each other suchthat operation of the hydraulic means immediately precedes movement ofthe upper platen to its lowest position inrelationto the lower platen,and a manually operable member to control said electrical means, saidelectrical control means for the clutch and brake devices including alsoa control relayall so arranged that operation of themanually operablememberis followed byoperation of the press in the full-. automaticcycleduring which the clutch device is constantly engaged with respect tosaid shaft and the brakedevice disengaged, y whereby the press performsrepeated pressure applying operations upon a work piece or work' piecesintroduced by the operator between said platens.

25. In a press, an upper and a lower platen movable with respect to eachother to exert al pressure applying operation upon a work piecesupported on the lower platen, mechanical means including a power shaftfor moving the upper platen toward the lower platen to engage a workpiece on the latter, a clutch device and a brake device for controllingsaid shaft, hydraulic means including a piston cylinder and a pistontherein for supporting the lower platen in a floating condition, saidhydraulic means including a regulating valve and a valve operative tocheck the flow of the pressure medium through a part of said hydraulicmeans whereby pressure vwill develop in said part of the hydrauliccircuit and in the piston cylinder when the upper platen presses thework piece against the lower platen, electrical means for controllingboth the mechanical means and the hydraulic means in timed relation toeach other such that operation of the hydraulic means immediatelyprecedes movement of the upperplaten to its lowest position in relationto the lower platen, and a manually operable member to control saidelectrical means, said electrical means including a clutch contact,a-brake contactor and a control Vrelay all so arranged that operation ofthe manually operablemember isfollowed by rotation of said power shaftwith the clutch device constantr ly engaged and the brake devicedisengaged,

whereby operation of the press in the full auto-l matic cycle 4takesplace, during which the press performs repeated pressure applyingoperations upon a work piece or work pieces introduced by the operatorbetween said platens.

26. In a press, an upper and a lower platen relatively movable withrespect tof-each other to exert a pressure applying operation upon awork piece supported by the lower platen, hydraulic means includingvalves for operating one of the platens with respect to the other toeffect a pressure applying operation, said hydraulic means comprising aregulating valve to secure a minimum pressure approaching zero in thehydraulic circuit, a pressure governor connected to said hydraulicmeans, electrical means including said pressure governor for controllingsaid hydraulic means, and a manually operable control member havingconnections to said electrical means for initiating a pressure applyingoperaf, tion through control of said hydraulic means,

one of said platens being movable with respect i to the other platen andone of the platens having a heated work contacting surface, a hydrauliccircuit comprising a piston cylinder and a piston to move the movableplaten into pressing relation to the other, means to circulate -apressure medium through said circuit, means including a y regulatingvalve in said hydraulic circuit to vmaintain a predetermined minimumpressure against the piston associated withv the movable platen wherebya work piece engaged by both platens u is subjected to heat at a`minimum pressure, a

second valve to effect building up of pressure in the piston cylinder toa predetermined maximum,

.a solenoid for operating the second valve, and

the application of heavy pressure at a predetermined regulatable point.

29. In a press, an upper platen, a lower platen movable in an upwarddirection toward the upper platen, one of said platens having a heatedwork contacting face, a hydraulic circuit comprising a piston cylinderand a piston to move said lower platenin an upward direction, amechanical device to exert an upward pressure on said piston, a pumpoperating continuously to force a pressure medium into said circuit,said hydraulic circuit comprising a valve operative to maintain in thepiston cylinder a predetermined minimum pressure such that the pressuremedium in co- 'operation with said mechanical device operates to floatthe piston and the lower platen, whereby pressure in a smooth plating orembossing operation.

31. In a press, a heated upper platen, a lower platen movable in anupward direction toward the upper platen, a hydraulic circuit comprisinga piston cylinder and a piston to move said lower platen in an upwarddirection, a spring arranged to press upwardly upon said piston, saidhydraulic .circuit comprising a valve constructed to maintain in thepiston cylinder a predetermined minimum pressure such that the pressuremedium in co-operation with said spring operates toi iloat laying theoperation of the last-mentioned valve the lower platen will yield when awork piece is engaged vby both platens to effect treatment of the workpiece by heat at a minimum pressure, a second valve in the hydrauliccircuit operable to stop the ow of pressure medium at a, point beyondthe piston cylinder whereby pressure'is built up in said cylinder to apredetermined maximum, andelectrical means comprising a time delay relayto delay the operation of the second valve fora predetermined periodwhereby the work piece is subjected to heat `treatment at fminimumpressure for a desired period of time as a preliminary to theapplication of heavy pressure in a vsmooth plating operation. i

30. In a press, a lower platen, a'hydraulic circuit comprising apistoncylinder and'a piston to operate said lower platen in an upwarddirection, a spring arranged to exert a yielding upward pressure on saidpiston and platen, means to circulate a pressure medium through saidcircuit, a regulating valve in the hydraulic circuit 'operative toprovide in the piston cylinder a predetermined mnimum pressure4 of thepressure medium therein, whereby said .pressure medium co-operates withthe spring to float the piston and lower platen, an upper platen movabledownfor delaying the operation of the last-mentioned valve for aregulatable period of `time, thereby securing heat treatment of the workpiece at minimum pressure for a predetermined period E as a preliminaryto the application of heavy -wardly a predetermined distance-such that afor a'period of time which may be predetermined by the loperator therebysecuring a preliminary heat treatment of the work piece fora predeter-Amined period before the application of heavy pressure in a smoothplating or embossing operation. I

32. A machine accordingto claim 31, in which a high range pressuregovernor is included in both the hydraulic circuit and in the electricalmeans and is operative to terminate heavy pres- `sure on Athe workpieceat a predetermined regulatable point.

33. In a. press, an upper and a lower platen relatively movable withrespect to each other to exert a pressure applying operation upon a workpiece supported on the lower platen, hydraulic means including valvesforoperating one of said platens toward the other, a high range pressuregovernor connected to said hydraulic means, a

low range' pressure governor adapted to be connected to said hydraulicmeans. electrical means including said pressure governors forcontrolling said hydraulic means, and a manually operable memberconnected to said electrical means for initiating operation of saidhydraulic means, said electrical means comprising time delay relays andselector switches therefor whereby a time delay may' be provided for atsubstantially zero pressure at the beginning of the building up ofpressure in said hydraulic means or for a time dwell at substantiallymaximum pressure in the operation of the press on a given piece of,work.

34. In a press, an upper and a lower platen one of which is movable withrespect to the other, a hydraulic circuit comprising a piston cylinderand a piston therein for moving the movable platen into pressingrelation to the other platen, a valve and Ia pressure governor both inthe hydraulic circuit to control the building up of pressure in thepiston cylinderwhereby the piston and the platen moved thereby areoperated to produce a predetermined maximum pressure on a work piecebacked by the other vplaten, and electrical connections comprising saidpressure governor anda time delay relay for controlling said valve tomaintain said maximum pressure for a predetermined period of time andthen to cause operation of the valve to terminate the period of maximumpressure.

` 35. In a press, an upper and a lower of which is movable with respectto the other, a

`hydraulic circuit comprising a piston cylinder;

and a piston thereins-for moving the, movable-11s,.

platen one platen into pressing relation vto the other platen, a pumpadapted to be continuously operable to force a pressure medium throughsaid circuit, a valve located in the hydraulic circuit beyond the pistoncylinder on the side away from said pump and operable to stop the flowof the pressure medium, thereby to build up pressure in said pistoncylinder whereby the piston and the platen moved thereby operate toproduce a predetermined maximum pressure on a work piece backed by theother platen, a second valve operative to admit the pressure medium tothe piston cylinder and to by-pass the pressure medium as soon as themaximum pressure has been built up in the piston cylinder, andelectrical means including a time delay relay for controlling saidvalves to determine the period of operation of the iirst-mentioned valvein stopping the ilow of the pressure medium through the piston cylinderthereby to maintain said maximum pressure for a predetermined period oftime and then to cause operation of the valves to terminate the periodof maximum pressure and to restore circulation of the pressure mediumthrough said circuit.

36. In a machine according to 'claim 35, in which a pressure governor isconnected in both the hydraulic circuit and in the electrical means andis operative to condition the said second valve to oy-pass the pressuremedium at a predemined maximum, a second valve in the hydraulic circuitoperable to pass the pressure mediu-m to the piston cylinder andalternatively to by-pass the pressure medium back' to a reservoir, apressure governor to control the operation of the second valve toterminate the building up of pressure in the piston cylinder at apredetermined point, and an electrical circuit including saidpressuregovernor and electrical power units in connection with thefirst-mentioned valve and the second valve and also .a time delay relayin 'the circuit of the electrical unit associated with thrst-mentionedvalve, tov control the operations of these two valves, whereby pressuremay be built up in the hydraulic circuit to a predetermined maximum andthen that maximum retained for a predetermined period.

38. In a press, an upper and a lower platen at least one of which ismovable with respect tothe other, a hydraulic circuit including a pistoncylinder and a pistonl for moving the movable platen toward thxeifotherplaten, a pump adapted to be',operated continuously to force a pressuremedium through said circuit, a valve in the hydraulic circuit operableto stop the ow of pressure medium in the hydraulic circuit to build uppressure in the piston cylinder to a predetermined maximum, a pressuregovernor adapted to vary the capacity of the pump thereby topredetermine the time required tobuild up the pressure to maximum insaid circuit, and an electrical circuit comprising electrical powerunits in con` nection With'the mst-mentioned valve and the third valveand also an adjustable time delay relay inthe circuit of the electricalunit associated with the first-mentioned valve to control the operationsof these two valves, whereby pressure may be built up in the hydrauliccircuit to a predetermined maximum and then that maximum retained for apredetermined period, the result being that a work piece may be treatedto pressure built up either rapidly or lrelatively slowly and to maximumpressure for a period of time in a relatively wide range.

39. In a press, an upper and a lower platen at least one of which ismovable with respect to the other, one of said platens having a heatedface, a hydraulic circuit including a piston cylin` der and a piston formoving the movable platen towards the other platen, means to circulate apressure medium through said ,circuit at a very low or minimum pressure,means to cause both platens to engage a work piece placed between themat'said minimum pressure, a valve in theJ hydraulic circuit operable tostop the ow of pressure medium in the hydraulic -circuit to build uppressurev in the piston cylinder to a predetermined maximum, a checkvalve to maintain pressure in that part of the hydraulic circuit whichincludes the piston cylinder, a third valve in the hydraulic circuitoperable to pass the pressure medium to the piston cylinder andalternatively to by-pass the pressure medium back to a reservoir, and anelectrical circuit comprising electrical power units associated withsaid rst-mentioned and third-mentioned valves to control the latter,said electrical circuit comprising also two time delay relays one ofwhich determines a delay in the operation `of the mst-mentioned valvethereby to secure heat treatment of the work piece at minimum pressurefor a predetermined period, the other time delay relay being operativeto control the first-mentioned valve to cause it to maintain maximumpressure in the hydraulic circuit for a predetermined period, whereby awork piece lsv treated to heat at minimum pressure for a predeterminedperiod and subsequently to heat at maximum pressure for another'predetermined period.

40. In a press, an upper and a lower platen at l least one of which ismovable with respect to the other, a hydraulic circuit including apiston cylinder and a piston for moving the movable platen toward theother platen, a valve in the hydraulic circuit operable to stop the flowof pressure medium in the hydraulic circuit to build `up pressure in thepiston cylinder to a predetermined maximum, a check Valve to' maintainpressure in that part of thehydraulic circuit which includes the pistoncylinder, a third valve' in the hydraulic circuit operable to pass thepressure medium to the piston cylinder and al- ;iredetermine 'thepressure in the piston cylinder and adjustable throughout a wide rangeof pressures, a check valve co-operating with the rstmentioned valve tomaintain pressurel in that v ternatively to by-pass the pressure mediumback to a reservoir, a pressure governor to control thelby-passingoperation of said third valve, and an electrical circuit comprisingsolenoids asso-I ciated with said first-mentioned andthird-men-` partofthe hydraulic circuit which includes the.

- piston cylinder, a third valve in the hydraulic circuit operable topass the pressure medium to the piston cylinder and alternatively toby-pass the Pressure medium back to a reservoir, means to tioned valvesto control the latter, said electrical circuit comprising also two timedelay relays one of which determines a delay in the operation of thefirst-mentioned valve thereby to secure heat treatment of the work pieceat minimum pressure for a predetermined period, the other'time

